The invention concerns a tilting-swinging roof window with a spring-assisted opening device, in which the window sash is hingedly supported at approximately the middle of the length of its side members on the free end of two arms pivotably mounted on the upper end of the casement and in which the sash is guided in the swinging position by two swivel pins on the side members of the sash which are slidable in grooves on the side members of the casing, and, in the tilting position, of the window sash is fixed on the arms.
A tilting-swinging roof window of this type is known from DE-OS 2 708 785. In the case of this roof window the arms holding the window sash are pushed upwardly by means of two supporting arms which are pivotable on the casing, the spring force being created by spiral springs located on the axis of pivoting thereof. Since, with increasing opening of the sash, the point of application of the working force of the supporting arms on the holding arms shifts in the direction to the upper end of the casing, the lever ratio becomes more unfavorable with increasing opening of the window. Therefore, strong spiral springs have to be used, which leads to the fact that the sash does not remain in a desired position in the case of small opening angles and therefore more favorable lever ratios, but automatically opens further. The supporting arms with the spiral springs require a relatively great amount of space on the casing. Since the grooves for guiding the swivel pins are located on the casing, the supporting arms have to be mounted in an area above the grooves. However, this arrangement again leads to increasingly unfavorable lever ratios.